1. Field of the Invention
The present invention relates to an apparatus and method for forming a nanoscale three-dimensional (3D) pattern using electrojetting, and more particularly, to an apparatus and method for forming a 3D pattern using electrojetting, whereby instability inherent in electrospinning of a nanojet is overcome and the 3D pattern is capable of being stably formed.
2. Discussion of Related Art
Lithography technology that is used to fabricate various devices, such as semiconductor integrated circuits (ICs), imaging devices, or liquid crystal display (LCD) devices, is critical technology in various micro machining processes. However, the lithography technology has a complicated process and requires a high cost.
That is, the conventional lithography technology has a complicated and cumbersome process in which a mask is fabricated, a photoresist (PR) is applied onto a material and then an exposure process of transferring patterns of the mask onto the material needs to be undergone so as to form one layer for fabricating one device including a stack of a plurality of layers.
In order to reduce this inefficiency, various nano fabrication technologies have started being studied. Nano fabrication technology is technology in which a particular material can be directly deposited on an object without using a mask. Examples of nano fabrication technologies include technology using a scanning tunneling microscope (STM), technology using an atomic force microscope (AFM), and atomic layer deposition (ALD) technology.
Dip pen nanolithography (DPN) technology or inkjet printing technology has also been suggested. However, the DPN technology has an advantage in that it can realize very fine resolution but has a disadvantage of a very slow speed. The inkjet printing technology has an advantage of a fast speed but has a disadvantage that it cannot lower resolution. Thus, it is not easy to apply these technologies according to the trend of the lithography technology that has gradually become simultaneously precise and large-scale.
Thus, there is a method for forming a nanopattern using a polymer jet obtained by electrospinning as one of the newly-suggested methods. In this case, electrospinning is a technique, whereby a strong electric field is applied to a polymer droplet so that a nanoscale polymer jet can be obtained.
FIG. 1 is a view of a state in which a nanoscale polymer jet is obtained by electrospinning. As illustrated in FIG. 1, when a strong electric field is applied to a polymer droplet 1, a repulsive force is generated between molecules within a liquid due to polarization in the liquid, and a polymer jet 3 having a small thickness is discharged from an end of the polymer droplet 1.
According to the electrospinning technology, a thin fiber having a diameter less than 1 μm can be easily obtained. Thus, the electrospinning technology has been newly spotlighted in a field in which a small scale fiber is required, as in a filter, drug delivery, a material for protective clothes, or cell proliferation.
Here, in order to form a nanopattern using the electrospinning technique, the polymer jet 3 should be stably supplied and simultaneously should be placed in good order on a surface on which a pattern is formed.
However, as illustrated in FIG. 2, the polymer jet 3 discharged from a syringe 5 by electrospinning is discharged due to a self repulsive force of electric charges a) that exist on the surface of the polymer jet 3 and flies by drawing a very instable trajectory (a whipping phenomenon). As a result, the polymer jet 3 cannot be formed in good order on a surface 7 on which a pattern needs to be formed, and thus it is difficult to use electrospinning so as to form a three-dimensional (3D) nanopattern.
Meanwhile, a scheme for stacking polymers on a sharp tip, such as a needle, has been suggested, as disclosed in Patent document 1. However, there is a limitation in forming a 3D structure.